Elver Finder

The elver detector has been developed to continuously monitor elvers.

Elver Finder

ELFI stands for Elver Finder and is the new name for our elver detector. Elvers are young migrating eels. The collection of elvers with the help of ELFI was first developed in 2011 to monitor the influx of elvers and eels in a consistent and continuous (24/7) manner.
The decreasing numbers of elvers has led to lower catches with traditional sample netting methods and ultimately poorer estimates.
ELFI is now a proven method, with elver monitoring and eel migration studies having been undertaken at numerous locations throughout the Netherlands.

Eel populations

Numbers of migrating elvers is an important indicator of the condition of the eel population. The Netherlands has been monitoring the elvers at Den Oever since 1938 with a dip net, making it one of the most important indicators of eel populations in Europe.
Research institute Wageningen Marine Research (WMR) undertakes the national monitoring of elvers in the Netherlands and is expecting ELFI to replace the current method dip nets as the recognised standard monitoring technique for elvers (ICES 2019).


ELFI is a joint initiative of Bureau Waardenburg and Visserij Service Nederland, where Bureau Waardenburg provides communication, reporting and analysis and Visserij Service Nederland carries out the installation, maintenance and data collection.

Fish Passage 2021

We were sponsor of the webinar Fish Passage 2021 Link to the presentations >>